/**
*
*
* Returns the index of the first non-null includeInLayout element,
* beginning with the element at index i.
*
* Returns -1 if no such element can be found.
*/
private static int FindLayoutElementIndex(GroupBase g, int i, int dir)
{
var n = g.NumberOfContentChildren;
while ((i >= 0) && (i < n))
{
var element = g.GetContentChildAt(i);
if (null != element && element.IncludeInLayout)
{
return i;
}
i += dir;
}
return -1;
}
/**
*
*
* Binary search for the first layout element that contains y.
*
* This function considers both the element's actual bounds and
* the gap that follows it to be part of the element. The search
* covers index i0 through i1 (inclusive).
*
* This function is intended for variable height elements.
*
* Returns the index of the element that contains y, or -1.
*/
private static int FindIndexAt(float y, int gap, GroupBase g, int i0, int i1)
{
var index = (i0 + i1) / 2;
InvalidationManagerClient element = (InvalidationManagerClient)g.GetContentChildAt(index);
var elementY = LayoutUtil.GetLayoutBoundsY(element);
var elementHeight = LayoutUtil.GetLayoutBoundsHeight(element);
// TBD: deal with null element, includeInLayout false.
if ((y >= elementY) && (y < elementY + elementHeight + gap))
return index;
else if (i0 == i1)
return -1;
else if (y < elementY)
return FindIndexAt(y, gap, g, i0, Math.Max(i0, index - 1));
else
return FindIndexAt(y, gap, g, Math.Min(index + 1, i1), i1);
}